CD40L stimulates the crosstalk between adipocytes and inflammatory cells

Macrophages and lymphocytes are implicated in obesity-related adipose tissue inflammation via interactions with adipocytes. Co-stimulatory systems, especially the CD40-CD40L system, play an important role in T cell activation and inflammatory reactions. CD40L was recently shown to promote adipose tissue inflammation in vivo, yet, the mechanisms underlying its function in the intercellular communication between inflammatory cells and adipocytes remain not entirely clear. Here we found that adipocyte stimulation with CD40L increased the expression of CD40, as well as of chemokines, such as MCP-1, CCL4, or CCL5, whereas adipocyte CD40 expression was also stimulated by TNF but not palmitate. Moreover, conditioned media of CD40L-pretreated adipocytes provoked elevated migration of mononuclear cells and increased the expression of inflammatory genes in bone marrow derived mononuclear phagocytes (BMDM) shifting them to an M1-like pro-inflammatory phenotype. Nonetheless, the CD40/CD40L interaction did not contribute to the adhesion between adipocytes and T cells. Together, CD40L stimulates adipocyte chemokine expression, thereby attracting monocytes/macrophages into the adipose tissue. Moreover, CD40L stimulation of adipocytes likely promotes macrophage M1 polarization in the adipose tissue and thereby perpetuation of adipose tissue inflammation.

Anti-tumor effects of peptide analogs targeting neuropeptide hormone receptors on mouse pheochromocytoma cells

Pheochromocytoma is a rare but potentially lethal chromaffin cell tumor with currently no effective treatment. Peptide hormone receptors are frequently overexpressed on endocrine tumor cells and can be specifically targeted by various anti-tumor peptide analogs. The present study carried out on mouse pheochromocytoma cells (MPCs) and a more aggressive mouse tumor tissue-derived (MTT) cell line revealed that these cells are characterized by pronounced expression of the somatostatin receptor 2 (sst2), growth hormone-releasing hormone (GHRH) receptor and the luteinizing hormone-releasing hormone (LHRH) receptor. We further demonstrated significant anti-tumor effects mediated by cytotoxic somatostatin analogs, AN-162 and AN-238, by LHRH antagonist, Cetrorelix, by the cytotoxic LHRH analog, AN-152, and by recently developed GHRH antagonist, MIA-602, on MPC and for AN-152 and MIA-602 on MTT cells. Studies of novel anti-tumor compounds on these mouse cell lines serve as an important basis for mouse models of metastatic pheochromocytoma, which we are currently establishing.

Increased rate of depression and psychosomatic symptoms in Jewish migrants from the post-Soviet-Union to Germany in the 3rd generation after the Shoa

The mental health status of persons with Jewish background living in Germany is discussed with special regard to social exclusion like anti-Semitism and overprotective parental rearing behavior, as a transmissional factor of the KZ-Syndrome. These stressors are considered in the context of a higher risk for depression/fear and psychosomatic disorders and also abnormal cortisol levels. The present sample (N=89) is derived from the Jewish population currently living in the German region of Saxony aged between 17-36 years that emigrated from the post-Soviet-Union areas. The mean age was 22.9 years. Two questionnaires to detect psychosomatic symptoms (Giessen complaint list (GBB)-24, hospital anxiety and depression scale) and one questionnaire addressing parental rearing behavior (FEE) were employed. Comparisons were drawn with normative data from the literature about the German residential population. In addition, questions were asked concerning the experience of anti-Semitism in Germany and in the post-Soviet-Union areas. A higher prevalence of depression/fear (10.3% versus 18.2%) and psychosomatic symptoms (M=14.03 versus 17.8; t=2.42; P<0.05) was observed in Jewish migrants to Germany as compared with non-Jewish German residents. Furthermore, anti-Semitic experiences in Germany correlated positively with depression (r=0.293; P<0.01) and fear (r=0.254; P<0.05). The anti-Semitic experiences in the post-Soviet-Union areas also correlated positively with limb pain (r=0.41, P<0.01), fatigue symptoms (r=0.296, P<0.01) and psychocardial symptoms (r=0.219, P<0.05). It was also confirmed that the male respondents recalled a controlling and overprotecting maternal rearing behavior more frequently than the German standard random sample (M=15.39 versus 18.6; t=2.68; P<0.01). The latter also correlated significantly positive with epigastric pain (r=0.349; P<0.01). The present results show that depression, fear and psychosomatic problems are common in Jewish residents with a background of migration from the post-Soviet-Union areas to Germany. Apart from the transgenerational passing of psychological traumata and the Holocaust experiences, other stressors like anti-Semitism, control and overprotection as parental rearing measures appear to be important factors specifically contributing to the pathogenesis of the attributed symptoms.

Circulating very-low-density lipoprotein from subjects with impaired glucose tolerance accelerates adrenocortical cortisol and aldosterone synthesis

Apart from their role in cardiovascular homeostasis and immunomodulation, aldosterone and cortisol are also implicated in the pathogenesis of insulin resistance and type 2 diabetes mellitus (T2DM). Furthermore, glycoxidative modifications of lipoproteins are increasingly recognized as an etiological factor for increased cardiovascular morbidity and mortality in prediabetic individuals. The causative relationship between in vivo lipoprotein modifications and steroidogenesis in subjects with impaired glucose tolerance (IGT), however, is not well defined. Therefore, we aimed to investigate the impact of in vivo modified lipoproteins on aldosterone and cortisol release from human adrenocortical H295R cells. Following an oral glucose tolerance test, 20 individuals with normal glucose tolerance (NGT) and 20 IGT subjects were randomly selected from the ongoing PRAEDIAS prevention study in our department. Cells were incubated for 24 h with lipoproteins isolated from NGT and IGT individuals and aldosterone and cortisol release was measured in the supernatants. VLDL induced a greater stimulating effect on adrenocortical aldosterone and cortisol release compared to HDL and LDL. Moreover, IGT-VLDL evoked a significantly higher effect (p<0.05) on hormone release than NGT-VLDL. Incubation of cells with in vitro modified lipoproteins and specific pharmacological inhibitors suggests that VLDL presumably recruits ERK1/2 as one of the downstream effectors of Jak-2. In summary, in vivo modified VLDL are able to promote prediabetic hormonal dysregulation by modulating adrenocortical steroidogenesis via Jak-2-ERK dependent pathway.

[Diagnosis of pheochromocytoma and paraganglioma: the clonidine suppression test in patients with borderline elevations of plasma free normetanephrine]

BACKGROUND

Measurements of plasma free metanephrines provide a sensitive test for the diagnosis of pheochromocytoma/paraganglioma (P/PGL), with highly elevated levels diagnostic of the disease. However, there is less diagnostic certainty in patients with mild elevations of these catecholamine metabolites.

PATIENTS AND METHODS

Here we report use of the clonidine suppression test (CST) as a second-tier diagnostic test in 24 patients with mild elevations of plasma free metanephrines and/or catecholamines. Blood samples before and 3 hours after clonidine were analyzed for plasma concentrations of metanephrines and catecholamines with a negative test result defined as either a clonidine-induced fall in normetanephrine or noradrenaline by more than 40 % and 50 % respectively or to below the upper cut-offs of reference intervals.

RESULTS

P/PGLs were confirmed in 9 patients and excluded in 15 by independent criteria. More than half of the patients without P/PGL showed normalized plasma concentrations of normetanephrine at baseline before clonidine compared to initial screening; all showed appropriate clonidine-induced falls in normetanephrine and noradrenaline or levels after the drug below upper cut-offs, indicating a diagnostic specificity of 100 % (CI 78-100 %). However, similar responses for noradrenaline were noted in 7 patients with P/PGL, indicating a diagnostic sensitivity of only 22 % (CI 2,8-60 %) compared to 100 % (CI 66-100 %) for normetanephrine.

CONCLUSION

These results support use of the CST in combination with measurements of normetanephrine for confirming or excluding P/PGL in patients with borderline elevated test results, which should, however, first be confirmed by sampling blood under standardized resting conditions.

Effect of thiazolidinedione treatment on proteinuria and renal hemodynamic in type 2 diabetic patients with overt nephropathy

Proteinuria in diabetic nephropathy predicts the progressive loss of glomerular filtration rate (GFR) and serves as independent predictor for mortality. We performed the present study (ClinicalTrials.gov identifier: NCT 00324675) to clarify whether the activation of PPARγ receptor by thiazolidinediones was able to improve proteinuria and preserve renal function in advanced diabetic nephropathy. A total of 28 type 2 diabetic patients (4 women and 24 men, mean age 66.1±9.1 years) with urinary albumin excretion >300 mg/24 h and an estimated GFR <60 ml/min were included into this prospective double blind trial to receive either rosiglitazone (RSG) 4 mg b.i.d or matching placebo (PLC) for 52 weeks in addition to their concomitant antidiabetic background therapy. At baseline and after 26 and 52 weeks, renal plasma flow (RPF) and GFR were determined before and after blockade of nitric oxide (NO) by intravenous administration of N-monomethyl-L-arginine acetate. RSG treatment resulted in a significant reduction of proteinuria (2.4±1.1; 1.2±0.6; 1.5±0.7 g/d at baseline, 26 weeks and 52 weeks; respectively, p<0.05) whereas PLC did not influence proteinuria (1.6±0.6; 1.6±0.8; 1.7±0.8 g/d). GFR and RPF did not change significantly during the study, however, RSG improved the intrarenal NO bioavailability. RSG treatment was generally well tolerated and the major adverse event - development of edema - could be controlled by dose adjustment of the study drug and diuretic agents. In conclusion, we demonstrated a possible renoprotective effect of RSG in patients with advanced diabetic nephropathy.

[Strategies for successful weight reduction - focus on energy balance]

The prevalence of obesity and related health problems is increasing worldwide and also in Germany. It is well known that substantial and sustained weight loss is difficult to accomplish. Therefore, a variety of studies has been performed in order to specify causes for weight gain and create hypotheses for better treatment options. Key factors of this problem are an adaptation of energy metabolism, especially resting metabolic rate (RMR), non-exercise thermogenesis and diet induced thermogenesis. The extremely high failure rate (> 80%) to keep the reduced weight after successful weight loss is due to adaptation processes of the body to maintain body energy stores. This so called "adaptive thermogenesis" is defined as a smaller than predicted change of energy expenditure in response to changes in energy balance. Adaptive thermogenesis appears to be a major reason for weight regain. The foremost objective of weight-loss programs is the reduction in body fat. However, a concomitant decline in lean tissue can frequently be observed. Since lean body mass (LBM) represents a key determinant of RMR it follows that a decrease in lean tissue could counteract the progress of weight loss. Therefore, with respect to long-term effectiveness of weight reduction programs, the loss of fat mass while maintaining LBM and RMR seems desirable. In this paper we will discuss the mechanisms of adaptive thermogenesis and develop therapeutic strategies with respect to avoiding weight regain successful weight reduction.

Metagenomic sequencing of the human gut microbiome before and after bariatric surgery in obese patients with type 2 diabetes: correlation with inflammatory and metabolic parameters

Roux-en-Y gastric bypass (RYGB) has become a prominent therapeutic option for long-term treatment of morbid obesity and type 2 diabetes mellitus (T2D). Cross talk and pathogenetic consequences of RYGB-induced profound effects on metabolism and gut microbiome are poorly understood. The aim of the present study therefore was to characterize intra-individual changes of gut microbial composition before and 3 months after RYGB by metagenomic sequencing in morbidly obese patients (body mass index (BMI)>40 kg m(-)(2)) with T2D. Subsequently, metagenomic data were correlated with clinical indices. Based on gene relative abundance profile, 1061 species, 729 genera, 44 phyla and 5127 KO (KEGG Orthology) were identified. Despite high diversity, bacteria could mostly be assigned to seven bacterial divisions. The overall metagenomic RYGB-induced shift was characterized by a reduction of Firmicutes and Bacteroidetes and an increase of Proteobacteria. Twenty-two microbial species and 11 genera were significantly altered by RYGB. Using principal component analysis, highly correlated species were assembled into two common components. Component 1 consisted of species that were mainly associated with BMI and C-reactive protein. This component was characterized by increased numbers of Proteobacterium Enterobacter cancerogenus and decreased Firmicutes Faecalibacterium prausnitzii and Coprococcus comes. Functional analysis of carbohydrate metabolism by KO revealed significant effects in 13 KOs assigned to phosphotransferase system. Spearmen's Rank correlation indicated an association of 10 species with plasma total- or low-density lipoprotein cholesterol, and 5 species with triglycerides. F. prausnitzii was directly correlated to fasting blood glucose. This is the first clinical demonstration of a profound and specific intra-individual modification of gut microbial composition by full metagenomic sequencing. A clear correlation exists of microbiome composition and gene function with an improvement in metabolic and inflammatory parameters. This will allow to develop new diagnostic and therapeutic strategies based on metagenomic sequencing of the human gut microbiome.

Lymphocytes in obesity-related adipose tissue inflammation

Inflammation in the white adipose tissue (WAT) is considered a major player in the development of insulin resistance. The role of macrophages accumulating in the WAT during obesity, promoting WAT inflammation and insulin resistance is well established. In contrast, less is known about the role of lymphocytes. Recent studies have implicated different lymphocyte subsets in WAT inflammation. For instance, cytotoxic CD8(+) T cells infiltrating the WAT may contribute to the recruitment, differentiation and activation of macrophages. On the other hand, a differential role for CD4(+) Th1 and CD4(+) Th2 cells has been suggested. Levels of WAT regulatory T cells decrease during the course of obesity and may represent a crucial factor for the maintenance of insulin sensitivity. Moreover, activation of natural killer T cells, an innate-like T cell population, which recognises lipid antigens, promotes insulin resistance and WAT inflammation. Finally, B cells may infiltrate WAT very early in response to high-fat feeding and worsen glucose metabolism through modulation of T cells and the production of pathogenic antibodies. These interesting new findings however bear controversies and introduce novel, yet unanswered, questions. Here, we review and discuss the impact of the different lymphocyte subsets in obesity-related WAT inflammation and attempt to identify the open questions to be answered by future studies.

[Benefits and risks of current pharmacotherapy in the treatment of type 2 diabetes]

The development of new drugs for the treatment of type 2 diabetes (T2DM) and metabolic disorders is currently one of the most innovative areas of drug development. However, a considerable number of newly developed drugs have either not reached the market and were stopped late in development or have been withdrawn after initial approval soon after market authorization due to serious safety concerns. How can drug safety problems be anticipated and, even more important, how can adverse events definitely caused by a drug be differentiated from incidences of naturally occurring diseases? This review article will provide an update about the state of the art treatment of type 2 diabetes and reflect on the newest available study evidence on glitazones, incretin mimetics (GLP-1 agonists and DPP-4 inhibitors), SGLT-2 inhibitors (gliflocines) and pan-PPAR agonists (glitazars). Furthermore, new and still experimental approaches for the treatment of T2DM, such as bardoxolone, salsalate and anakinra will be briefly reviewed.

Diabetic lipoproteins and adrenal aldosterone synthesis--a possible pathophysiological link?

An increased prevalence of diabetes mellitus (DM) has been reported in patients with primary aldosteronism (PA). DM is associated with abnormal structure and metabolism of circulating lipoproteins, which normally serve as a major source of cholesterol for adrenocortical steroidogenesis. The present study has been designed to investigate the effect of diabetically modified lipoproteins on adrenocortical aldosterone synthesis. Lipoproteins (VLDL, LDL, HDL) isolated from healthy volunteers, were subjected to oxidation or glycoxidation in the presence of sodium hypochlorite (3 mmol/l) or glucose (200 mmol/l), and aldosterone synthesis in human adrenocortical cells (H295R) was examined. Native and glycoxidized VLDL had greatest stimulatory effect on aldosterone production by 15-fold and 14-fold, respectively. At the molecular level, these VLDL produced maximum increases in Cyp11B2 mRNA level up to 17-fold. Experiments with the highly selective scavenger receptor class B type I (SR-BI) inhibitor BLT-1 revealed that cholesterol uptake from native and glycoxidized HDL and VLDL for hormone production is considerably mediated by SR-BI. Western blot analysis of extracellular signal-regulated kinase (ERK 1/2) phosphorylation and experiments with the MEK inhibitor U0126 indicated a specific mechanistic role of the ERK cascade in lipoprotein-mediated steroid hormone release. In summary, diabetic dyslipidemia and modification of circulating lipoproteins may promote adrenocortical aldosterone synthesis.

Nuclear factor of activated T cells mediates oxidised LDL-induced calcification of vascular smooth muscle cells

AIMS/HYPOTHESIS

Vascular calcification is a prominent feature of both atherosclerosis and diabetes, and is clinically associated with osteoporosis. The expression of bone-regulatory factors and the impact of oxidative stress in aortic calcification are well-documented. Recently, nuclear factor of activated T cells (NFAT) cytoplasmic, calcineurin-dependent 1 (NFATc1) was identified in calcified aortic valves and has been implicated in vascular calcification. Therefore, we assessed the mechanisms of osteogenic transdifferentiation of vascular smooth muscle cells induced by oxidised LDL (oxLDL) and evaluated the role of NFAT in this process.

METHODS

Human coronary artery smooth muscle cells (HCASMCs) were cultured for 21 days in medium supplemented with oxLDL. NFAT was inhibited using the NFAT inhibitor VIVIT, or by knockdown with small interfering RNA (siRNA). Osteogenic transdifferentiation was assessed by gene expression, matrix mineralisation and alkaline phosphatase activity.

RESULTS

Exposure to oxLDL caused the transformation of HCASMCs towards an osteoblast-like phenotype based on increased mineral matrix formation and RUNX2 expression. NFATc1 blockade completely prevented oxLDL-induced osteogenic transformation of HCASMCs as well as oxLDL-induced stimulation of osteoblast differentiation. In contrast, matrix mineralisation induced by osteogenic medium was independent of the NFAT pathway. Of note, oxLDL-conditioned medium from HCASMCs transferred to bone cells promoted osteoblast mineralisation. Consistent with these in vitro findings, diabetic rats with a twofold increase in oxidised lipid levels displayed higher aortic calcium concentrations and increased expression of osteogenic markers and production of NFATc1.

CONCLUSIONS/INTERPRETATION

Our results identify the NFAT signalling pathway as a novel regulator of oxLDL-induced transdifferentiation of vascular smooth muscle cells towards an osteoblast-like phenotype.

Ceruloplasmin expression in rat liver cells is attenuated by insulin: role of FoxO transcription factors

The phosphoinositide 3'-kinase (PI3 K)/Akt pathway controls the activity of a number of proteins important in the regulation of apoptosis and cell proliferation. FoxO (forkhead box, class O) transcription factors, substrates of the Ser/Thr kinase Akt, control the expression of several target genes that are crucial to the defense against oxidative stress, the regulation of cell cycle, and apoptosis in mammalian cells. Here, expression of ceruloplasmin (CP), the major copper-containing protein in blood released by the liver, was investigated. We observed a significant downregulation of CP mRNA levels after insulin treatment in H4IIE rat hepatoma cells. The PI3K inhibitor wortmannin counteracted this insulin effect on CP mRNA levels, indicating that the PI3K/Akt cascade is involved in the regulation of CP expression. Stimulation of FoxO1 was induced in H4IIE rat hepatoma cells expressing a conditionally active FoxO1 construct, resulting in significant upregulation of CP mRNA levels. This upregulation was prevented in the presence of insulin. In parallel, mRNAs of established FoxO target genes were analyzed: like CP mRNA, selenoprotein P and glucose 6-phosphatase mRNAs were upregulated by FoxO1, which was prevented by insulin. The same effects of insulin on CP mRNA levels were detected in primary rat hepatocytes. Furthermore, CP release into cell culture media was analyzed with primary hepatocytes and found to be attenuated by insulin. In line with its insulin-mimetic effects on cultured cells, Cu (2+) imitated the effect of insulin on CP expression and caused a downregulation of CP mRNA levels in rat hepatoma cells.

[Recent advances in type 2 diabetes mellitus]

Currently, the oral glucose tolerance test remains the "gold standard" for diagnosing type 2 diabetes, HbA (1c) being of subordinate value because of its limited diagnostic sensitivity. Fully evaluated risk scores and questionnaires are helpful in determining individual type 2 diabetes risk profiles and may prove valuable tools in preventing this type of diabetes. Genetic studies support our current understanding of the pathophysiology of type 2 diabetes. In the near future genetic data may become useful in optimizing individual preventative and therapeutic strategies. Recent data suggest that it is reasonable to adjust therapeutic aims on the specific situation of individual patients for achieving optimal results. The present therapeutic armamentarium for the treatment of type 2 diabetes has been rapidly extended over the recent years. To deal with this situation, pharmacovigilance is an essential tool to ensure drug safety and improve existing therapeutic standards.

Adrenal gland responses to lipopolysaccharide after stress and ethanol administration in male rats

All forms of stress, including restraint stress (RS) and lipopolysaccharide (LPS) administration, activate the hypothalamic-pituitary-adrenal (HPA) axis. LPS binds to a recognition protein (CD14) and toll-like receptor 2/4 in different cells and tissues, including the adrenal gland, to induce the production of cytokines and cause upregulation of cyclooxygenase and nitric oxide synthase (NOS) enzymes. Acute ethanol exposure activates the HPA axis, but in some conditions prolonged administration can dampen this activation as well as decrease the inflammatory responses to LPS. Therefore, this study was designed to evaluate the adrenal response to a challenge dose of LPS (50 μg/kg) injected i.p., after submitting male rats to RS, twice a day (2 h each time) for 5 days and/or ethanol administration (3 g/kg) by gavage also for 5 days, twice daily. At the end of the experiment, plasma corticosterone concentrations and adrenal gland content of prostaglandin E (PGE) and NOS activity were measured as stress mediators. The results showed that repetitive ethanol administration attenuated the adrenal stress response to LPS challenge alone and after RS, by preventing the increase in plasma corticosterone concentrations and by decreasing the PGE content and NOS activity in the adrenal gland. Therefore, we conclude that moderate alcohol consumption could attenuate the effects of psychophysical stress and impair an inflammatory response.

Alcohol consumption and other psycho-social conditions as important factors in the development of diabetic foot ulcers

AIMS

To characterize bio-psycho-social factors, particularly mental disorders and self-harm behaviour, associated with the development of diabetic foot ulcers.

METHODS

Two groups of diabetic patients with and without foot ulcers (n=47 in each group) with similar sex, age and diabetes duration were assessed for mental disorders using the Composite International Diagnostic Interview. Self-harm behaviour, quality of life, depressive symptoms and self-compassion were rated using different standard questionnaires.

RESULTS

Patients from the ulcer group visited their practitioners and/or psychotherapists less frequently in the last 12 months than patients in the control group 0 vs. 13%; P=0.026). The ulcer group patients had a history of increased alcohol consumption (43 vs. 19%; P=0.025), lower levels of education (8 vs. 10 grades; P=0.014) and income (1190 vs. 1535 €/month; P=0.039). Additionally, they were less likely to be diagnosed with anxiety disorders (11 vs. 32%; P=0.022). No significant differences in glycated haemoglobin, body mass index, smoking and direct self-harm behaviour were identified.

CONCLUSIONS

Patients with foot ulcers tend to exhibit lower health-conscious behaviour, particularly higher lifetime alcohol consumption, lower utilization of medical services and less general anxiety. Practitioners should be aware of these behaviours, since early detection of diabetes patients at psycho-social risk and consecutive psychological intervention may be an effective preventive strategy in avoiding the development of foot ulcers.

[Recent advances in the treatment of type 1 diabetes mellitus]

INTERVENTIONAL APPROACHES TO BETA CELL PRESERVATION: In a pilot study, initial attempts at primary prevention by preserving islet beta cells have been successful with highly hydrolyzed milk formula in children who are at high genetic risk of diabetes. Attempts at secondary prevention by intranasal application in children with a high-risk HLA genotype and positive islet autoantibodies have been disappointing. But in tertiary prevention anti-inflammatory, antigen-directed and T-cell targeted treatment has been partially successful in slowing down the destruction of beta cells. BIOLOGICAL BETA CELL SUBSTITUTION: Transplantation of a vascularised pancreas or islet cells results in disease regression and the prevention of secondary/tertiary complications of diabetes. A principal aim is the avoidance of frequent, severe hypoglycaemic episodes resulting from markedly reduced awareness of hypoglycaemia or its counter-regulation.

Relationship between HbA1c on target, risk of silent hypoglycemia and glycemic variability in patients with type 2 diabetes mellitus

OBJECTIVE

We aimed to compare time spent at low glucose level (silent hypoglycemia, glucose <3.0 mmol/l) and glycemic variability in patients who reached HbA1c <7.0% with those who did not.

RESEARCH DESIGN AND METHODS

In 108 type 2 diabetic patients the interstitial glucose concentration was measured with CGMS (Continuous Glucose Monitoring System) over 72 h. Patients were divided in group 1 with an HbA1c <7.0% (n=63) and group 2 with an HbA1c≥7.0% (n=45).

RESULTS

24% in group 1 experienced silent hypoglycemia vs. 11% in group 2 (n. s.), duration of silent hypoglycemia over 48 h was 27±71 min vs. 7±36 min (n. s.). This was also valid for the subgroups treated with insulin. Patients in group 2 had a significantly higher standard deviation of average glucose (2.3±0.8 vs. 1.3±0.6; p<0.001) and MAGE (mean amplitude of glycemic excursions) (4.8±2.1 vs. 2.6±1.1; p<0.001).

CONCLUSION

Silent hypoglycemia tended to occur more often and to last longer in patients with HbA1c <7%. However, patients with HbA1c >7% had a higher glycemic variability. HbA1c >7% wasn't a reliable indicator of lower risk of hypoglycemia.

A novel device for islet transplantation providing immune protection and oxygen supply

Islet transplantation as a biological β-cell replacement therapy has emerged as a promising option for achieving restoration of metabolic control in type 1 diabetes patients. However, partial or complete loss of islet graft function occurs in relatively short time (months to few years) after implantation. The high rate of early transplant dysfunction has been attributed to poorly viable and/or functional islets and is mediated by innate inflammatory response at the intravascular (hepatic) transplant site and critical lack of initial nutrient/oxygen supply prior to islet engraftment. In addition, the diabetogenic effect of mandatory immunosuppressive agents, limited control of alloimmunity, and the recurrence of autoimmunity limit the long-term success of islet transplantation. In order to abrogate instant blood-mediated inflammatory reaction and to provide oxygen supply for the islet graft, we have developed an extravascular (subcutaneous) transplant macrochamber (the 'βAir' device). This device contains islets immobilized in alginate, protected from the immune system by a thin hydrophilized teflon membrane impregnated with alginate and supplied with oxygen by daily refueling with oxygen-CO (2) mixture. We have demonstrated successful utilization of the oxygen-refueling macrochamber for sustained islet viability and function as well as immunoprotection after allogeneic subcutaneous transplantation in healthy minipigs. Considering the current limitations of intraportal islet engraftment and the restricted indication for islet transplantation mainly due to necessary immunosuppressive therapy, this work could very likely lead to remarkable improvements in the procedure and moreover opens up further strategies for porcine islet cell xenotransplantation.

The effects of the endothelium on adrenal steroidogenesis and growth are mainly mediated by proteins other than endothelin-1

The endothelium releases factors stimulating the adrenal cortex. It is also known that endothelin-1 (ET-1) promotes generation of cortisol and aldosterone, and proliferation of adrenocortical cells. The aim of the study was to find out whether the effect of the endothelium on adrenocortical cells is dominated by the action of ET-1. The effects of endothelial cell-conditioned medium (ECCM), obtained during growth of human umbilical cord vein endothelial cells, on aldosterone and cortisol release by cells of the adrenocortical cancer cell-line NCI-H295R and the promoter activity of steroidogenic acute-regulatory protein (StAR) were studied. The effect of ECCM on proliferation of human primary normal adrenocortical and NCI-H295R cells was also investigated. Concentration-dependent increases in cortisol release that reached 192.7 ± 62.8 in percent of basal secretion, in aldosterone release that reached 188.2 ± 52.3 in percent of basal secretion, and in proliferation after stimulation with ECCM at concentrations of 10-50% were found. ECCM significantly activated the StAR promoter 3-fold in NCI-H295R cells if the ECCM was not pretreated with pronase. These effects of the endothelium were not reversed after co-incubation with endothelin receptor antagonists and could not be mimicked by incubation with endothelin-1. In conclusion, the cultured endothelial cells secrete a protein that stimulates steroidogenesis in adrenal cells and their growth. It was also shown that the ET-1 does not mediate the effect of ECCM on the NCI-H295R cell line.

Linking Alzheimer's disease to insulin resistance: the FoxO response to oxidative stress

Oxidative stress is an important determinant not only in the pathogenesis of Alzheimer's disease (AD), but also in insulin resistance (InsRes) and diabetic complications. Forkhead box class O (FoxO) transcription factors are involved in both insulin action and the cellular response to oxidative stress, thereby providing a potential integrative link between AD and InsRes. For example, the expression of intra- and extracellular antioxidant enzymes, such as manganese-superoxide dismutase and selenoprotein P, is regulated by FoxO proteins, as is the expression of important hepatic enzymes of gluconeogenesis. Here, we review the molecular mechanisms involved in the pathogenesis of AD and InsRes and discuss the function of FoxO proteins in these processes. Both InsRes and oxidative stress may promote the transcriptional activity of FoxO proteins, resulting in hyperglycaemia and a further increased production of reactive oxygen species (ROS). The consecutive activation of c-Jun N-terminal kinases and inhibition of Wingless (Wnt) signalling may result in the formation of β-amyloid plaques and τ protein phosphorylation. Wnt inhibition may also result in a sustained activation of FoxO proteins with induction of apoptosis and neuronal loss, thereby completing a vicious circle from oxidative stress, InsRes and hyperglycaemia back to the formation of ROS and consecutive neurodegeneration. In view of their central function in this model, FoxO proteins may provide a potential molecular target for the treatment of both InsRes and AD.

Glucokinase-activating GCKR polymorphisms increase plasma levels of triglycerides and free fatty acids, but do not elevate cardiovascular risk in the Ludwigshafen Risk and Cardiovascular Health Study

Two strongly correlated polymorphisms located within the gene of the glucokinase regulator protein (GKRP), rs780094 and rs1260326, are associated with increased plasma triglyceride levels and provide a genetic model for the long-term activation of hepatic glucokinase. Because pharmacological glucokinase activators are evaluated for the treatment of diabetes, the aim of the study was to assess if these polymorphisms could provide evidence for an increased cardiovascular risk of long-term glucokinase activation. Therefore, these polymorphisms were tested in 3 500 patients of the Ludwigshafen Risk and Cardiovascular Health study, which was designed to assess cardiovascular risk factors. The two variants were associated with a significant increase of both plasma triglycerides (p<0.0001) and VLDL triglyceride levels (p<0.0001). Plasma free fatty acid concentrations were also significantly elevated (p<0.0078). LDL and HDL cholesterol levels were unchanged. No association was found with respect to coronary stenosis, myocardial infarction, left ventricular wall hypertrophy, and hypertension. In conclusion, long-term genetic glucokinase activation by the GKRP polymorphisms was not associated with an increased cardiovascular risk in the study population.

Anandamide injected into the lateral ventricle of the brain inhibits submandibular salivary secretion by attenuating parasympathetic neurotransmission

Our objective was to determine the effect of arachidonylethanolamide (anandamide, AEA) injected intracerebroventricularly (icv) into the lateral ventricle of the rat brain on submandibular gland (SMG) salivary secretion. Parasympathetic decentralization (PSD) produced by cutting the chorda tympani nerve strongly inhibited methacholine (MC)-induced salivary secretion while sympathetic denervation (SD) produced by removing the superior cervical ganglia reduced it slightly. Also, AEA (50 ng/5 microL, icv) significantly decreased MC-induced salivary secretion in intact rats (MC 1 microg/kg: control (C), 5.3 +/- 0.6 vs AEA, 2.7 +/- 0.6 mg; MC 3 microg/kg: C, 17.6 +/- 1.0 vs AEA, 8.7 +/- 0.9 mg; MC 10 microg/kg: C, 37.4 +/- 1.2 vs AEA, 22.9 +/- 2.6 mg). However, AEA did not alter the significantly reduced salivary secretion in rats with PSD, but decreased the slightly reduced salivary secretion in rats with SD (MC 1 microg/kg: C, 3.8 +/- 0.8 vs AEA, 1.4 +/- 0.6 mg; MC 3 microg/kg: C, 14.7 +/- 2.4 vs AEA, 6.9 +/- 1.2 mg; P < 0.05; MC 10 microg/kg: C, 39.5 +/- 1.0 vs AEA, 22.3 +/- 0.5 mg; P < 0.001). We showed that the inhibitory effect of AEA is mediated by cannabinoid type 1 CB1 receptors and involves GABAergic neurotransmission, since it was blocked by previous injection of the CB1 receptor antagonist AM251 (500 ng/5 microL, icv) or of the GABA A receptor antagonist, bicuculline (25 ng/5 microL, icv). Our results suggest that parasympathetic neurotransmission from the central nervous system to the SMG can be inhibited by endocannabinoid and GABAergic systems.

COUP-TFII is regulated by high glucose in endothelial cells

Diabetes mellitus is an important risk factor for cardiovascular diseases. Clinical evidence supports a link between hyperglycemia, endothelial dysfunction, and vascular disorders. However, the precise molecular mechanisms causing endothelial dysfunction in diabetic patients remain unclear. An interesting novel mediator could be chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII), which plays an essential role in glucose metabolism. COUP-TFII is known to be expressed in venous endothelial cells. In this study, we show COUP-TFII expression in human umbilical vein endothelial cells (HUVECs) and human coronary artery endothelial cells. HUVECs express glucose transporters 1, 3, 6, and 10, and the insulin receptor. Insulin in combination with glucose activates protein kinase B (PKB or Akt) phosphorylation via phosphoinositide 3-kinase (PI3-kinase). Short-term (60-240 min) stimulation of HUVECs with high glucose increased COUP-TFII expression independent of insulin. Long-term (48 h) stimulation of HUVECs with high glucose augmented expression of the insulin receptor and E-selectin, but downregulated COUP-TFII protein expression. Downregulation of COUP-TFII by shRNA leads to downregulation of E-selectin and upregulation of eNOS and glucose transporters. Our data suggest that COUP-TFII is regulated by glucose in a time- and dose-dependent manner in endothelial cells. COUP-TFII might affect endothelial function in a diabetic background.

Expression and function of endocannabinoid receptors in the human adrenal cortex

Endogenous cannabinoids are important signaling molecules in neuroendocrine control of homeostatic and reproductive functions including stress response and energy metabolism. The hypothalamic paraventricular and supraoptic nuclei have been shown to release endocannabinoids, which act as retrograde messengers to modulate the synaptic release of glutamate during stress response. This study endeavors to elucidate possible interaction of the endocannabinoid system with the regulation of adrenocortical function at the adrenal level. Human adrenocortical NCI-H295R cells and normal human adrenal glands were used to study the possible effects of anandamide and cannabinoid receptor 1 (CB1) antagonist SR141716A on aldosterone and cortisol secretion. Our data indicate the expression of CB1 in human adrenal cortex and adrenocortical NCI-H295R cells; CB2 was not expressed. Furthermore, anandamide inhibited basal release and stimulated release of adrenocortical steroids (corticosterone and aldosterone); this effect was reversed by CB1 antagonist (SR141716A). Therefore, the endocannabinoid system at the level of the adrenal, can directly influence adrenocortical steroidogenesis.

Regulation of glucose-6-phosphatase gene expression by insulin and metformin

The biguanide derivative metformin is a potent anti-diabetic drug widely used in the treatment of type 2 diabetes mellitus. Its major effect on glucose metabolism consists in the inhibition of hepatic glucose production. Since the mechanisms of metformin action are only partially understood at the molecular level, we studied the regulation of the gene promoter activity of glucose-6-phosphatase (G6Pase), the central hepatic gluconeogenic enzyme, by this drug. We have found that both metformin and insulin inhibit the basal and dexamethasone/cAMP-stimulated G6Pase promoter activity in hepatoma cells. Since one of the pharmacological targets of metformin is AMP-activated protein kinase (AMPK) and activation of AMPK is known to inhibit hepatic glucose production by the suppression of G6Pase gene transcription, we studied the effect of AMPK in this context. Under nonstimulated conditions, the inhibitory effect of both insulin and metformin was partially counteracted to a similar extent by treatment with compound C, a specific inhibitor of AMPK. In contrast, under conditions of stimulation with dexamethasone and cAMP, treatment with compound C reversed the inhibitory effect of metformin on G6Pase promoter activity to a similar extent as compared to nonstimulated conditions, whereas the effect of insulin was almost resistant to treatment with the AMPK-antagonist. These data indicate a differential AMPK-dependent regulation of G6Pase gene expression by insulin and metformin under basal and dexamethasone/cAMP-stimulated conditions.

Atrial natriuretic peptide-like immunoreactive material (ANP-LI) is released from the adrenal gland by splanchnic nerve stimulation

We investigated the release of atrial natriuretic peptide-like immunoreactive material (ANP-LI) after splanchnic nerve stimulation of isolated perfused adrenal glands. Electrical stimulation of the splanchnic nerves caused a statistically significant increase of ANP-LI (186 +/- 12 pg.min-1; p < 0.05) at 5 min. after stimulation. The integrated ANP-LI release after stimulation was amounted to 354 +/- 6.8% over basal. The regulation of ANP through the sympathoadrenal system may indicate an important role of ANP in adrenal steroidogenesis.

Nestin as a marker in the classification of adrenocortical tumors

Expression of the intermediate filament, nestin, was long believed to be restricted to neuroectodermal stem cells. However, nestin expression has recently been detected in several tumors. Since adrenocortical carcinoma, a tumor entity still very difficult to classify, may gain the ability to aberrantly express neuroectodermal proteins including chromogranin A and synaptophysin, we asked the question whether nestin might also be detected in adrenocortical carcinomas, and if so, whether it might serve as a tool for clinical pathology. Therefore, we studied the expression of nestin in normal adrenal glands, adrenocortical adenomas, and adrenocortical cancers using specific immunohistochemistry and semi-quantitative reverse transcriptase-polymerase chain reaction. Immunostaining was nestin-positive in 1 out of 9 normal adrenal glands (11%), 2 out of 20 adrenocortical adenomas (10%), and 13 out of 16 adrenocortical carcinomas (81%). Expression of nestin mRNA could be detected in all microdissected tissues, independently of their grade of dedifferentiation. We conclude that our findings provide further evidence that nestin, as a marker, is not restricted to neuronal stem cells and nestin expression is worth to be studied in adrenocortical tumors.

A more simplified Finnish diabetes risk score for opportunistic screening of undiagnosed type 2 diabetes in a German population with a family history of the metabolic syndrome

The aim of the present study was to evaluate the performance of the Finnish diabetes risk score (FINDRISC) for identifying undiagnosed type 2 diabetes in a German population and to develop a more simplified alternative model. We invited 921 individuals with a family history of the metabolic syndrome in a cross-sectional survey. Of these, 771 subjects completed the FINDRISC questionnaire and underwent an oral glucose tolerance test. The performance of the FINDRISC was assessed using the area under the receiver operating characteristics curve (ROC-AUC). The ROC-AUC of the FINDRISC was 0.81 (0.76-0.87). We detected no difference in diabetes prevalence between individuals with or without a family history of diabetes. Two logistic regression models (continuous- and categorical-model) were developed using the diagnosis of diabetes as the dependent variable, and age, body mass index (BMI), waist circumference, use of blood pressure medication, and history of high blood glucose as independent variables. After stepwise backward elimination of the insignificant variables, the following variables remained: age, BMI, and history of high blood glucose. The ROC-AUCs for the continuous- and categorical-models were 0.88 (0.85-0.92) and 0.86 (0.82-0.90), respectively, and were significantly larger than the ROC-AUC of the FINDRISC. There was no significant difference between the ROC-AUC of fasting plasma glucose and those of the two regression models. The FINDRISC questionnaire can be used to identify undetected diabetes in a German population. The simplified version, the categorical-model, may be a useful alternative for identifying asymptomatic type 2 diabetes.

Effects of the alpha glucosidase inhibitor acarbose on endothelial function after a mixed meal in newly diagnosed type 2 diabetes

Endothelial dysfunction (ED) has been suggested as a possible causal link between postprandial hyperglycemia and cardiovascular events in patients with type 2 diabetes. Recent trials demonstrated a reduction of cardiovascular events by treatment with alpha-glucosidase inhibitor acarbose - a drug which mainly reduces postprandial glucose excursions. We were interested to know whether patients with newly diagnosed type 2 diabetes showed postprandial ED and if so whether acarbose was able to improve this condition. Forearm blood flow (FBF) measurements for assessment of ED were performed in the fasting and postprandial state in 20 newly diagnosed type 2 diabetic patients and 10 healthy control subjects. After baseline examination, patients were randomly assigned to a 20-week treatment of acarbose 100 mg t.i.d or matching placebo, thereafter FBF measurements were repeated. FBF of patients in the fasting state was significantly impaired compared to healthy control subjects (max. FBF 5.3+/-0.7 vs. 8.0+/-0.9 ml/100 ml, p<0.02) and did not change in the postprandial state (max. FBF 5.6+/-0.7 ml/100 ml). In contrast, healthy controls showed a significant improvement of FBF in the postprandial state (11.5+/-1.2 ml/100 ml), which is compatible with postprandial ED in the group of patients. Twenty weeks of acarbose treatment did not affect either fasting or postprandial FBF in patients. Early type 2 diabetes is a state of both fasting and postprandial ED, which is not sensitive to acarbose treatment. Protective cardiovascular effects of acarbose might involve other mechanisms.